3D neuronal cell culture on paper device and bioelectrochemical analysis

Context- Paper, here used as a substrate for biomedical devices, has recently opened new applications such as immunoassay, microfluidics or electrochemical sensors. The advantages of a material like paper are mainly its affordability, ease of modification and the tunability of its chemical properties. Cell culture on paper has been demonstrated to facilitate the growth of cells in a 3D environment to better describe the conditions of a real organ/ tissue. To improve the viability of cells on paper, it is possible to treat the paper with extracellular matrix molecules. Furthermore, it is possible to print electrodes on paper using techniques and materials derived from printed electronics. Paper can thus be used as an electrochemical device to quantitatively measure molecules such as dopamine, a neurotransmitter secreted by dopaminergic neurons. These capabilities pave the way for on-paper cell analysis of neurotransmitters.Neurons on paper- By tuning the biocompatibility of paper, the viability of a cells deposit can be increased, showing the possibility of achieving neuronal cells culture on paper. The growth of theses neuronal culture can be monitored, and the neurons can survive for several days after the initial deposition. The performance of different kinds of modified paper devices were compared based on the neuron viability and the growth of axons and dendrites. Fluorescence-based imaging has been the chosen method to achieve the monitoring of theses 2 mains indicators of performance. Since paper has auto-fluorescent properties, by choosing precise fluorophores to image neurons and their projections, we have been able to produce clear fluorescent images of murine dopaminergic neurons within the paper and quantify the growth of their process. Detection of neurochemicals within the culture on paper will further prove the viability and integrity of the neurons in culture on paper. Developing a new device allowing the study of a neuronal network in precise conditions will help understand their mechanisms and find new neuropharmacological solution.Neurochemical analysis- By tuning the paper with different conductive inks, polymer poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS) and carbon nanotubes (CNT), paper electrodes can be used for dopamine and other neurotransmitters detection. Combining PEDOT:PSS and CNT have shown to ameliorate fouling resistance of the paper electrode, a phenomenon occurring when dopamine is oxidized, and improve electrochemical properties, lower capacitive current and higher anodic current. Optimizing spatial and temporal measures of dopamine secretion, in response to activation, can lead to a better understanding of neuronal dynamics